The fluorescence properties of fluorophores relevant in tissue metabolism (NADH, flavines, etc.) are characteristic of the clinical states of tissues. Especially the differentiation of healthy, cancerous, and necrotic tissue states is of large interest in lung-tumor diagnostics, e.g. to ensure that biopsies are taken from non-necrotic areas. In contrast to the common fluorescence detection our approach provides both a combination of spectral and time information from autofluorescence and the simultaneous detection of two fluorophores in order to improve differentiation between various tissues. The basis of analysis of autofluorescence is knowledge of the photophysical parameters of the fluorophores. Aqueous solutions of NADH, flavines and their mixtures have been investigated using the method of time-correlated single photon counting. The fluorescence was recorded with a new 'delay-line' microchannel-plate photomultiplier tube, that enables time- and wavelength-resolved measurements simultaneously. Nicotine-adenine-dinucleotide (NADH) and flavine-adenin-dinucleotide (FAD) display their characteristic temporal behavior (NADH: (tau) 1 equals 250 ps, (tau) 2 equals 660 ps; FAD: (tau) 1 equals 160 ps, (tau) 2 equals 2.25 ns, (tau) 3 equals 4.6 ns) in aqueous solution. In a mixture of NADH and FAD both components could be isolated by using global analytical methods. Time-gated fluorescence measurements on lung-tissue samples of 12 patients immediately after surgical resection have been performed with a fiber- based fluorescence detector. It could be demonstrated that NADH measurements are suitable for differentiating tumorous and necrotic tissue while flavine measurements are suitable for differentiating healthy and non-healthy tissue types. Applications of optical fibers facilitate simple combinations of the detection method with common surgical instruments (e.g. biopsy needles).